﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;
using System.Threading;

namespace SMTP
{

    public class StateObject
    {
        // Client  socket.
        public Socket workSocket = null;
        // Size of receive buffer.
        public const int BufferSize = 1024;
        // Receive buffer.
        public byte[] buffer = new byte[BufferSize];
        // Received data string.
        public StringBuilder sb = new StringBuilder();
    }

    public class AsynchronousSocketListener
    {
        // Thread signal.
        public static ManualResetEvent allDone = new ManualResetEvent(false);

        public AsynchronousSocketListener()
        {
        }

        public static void StartListening()
        {
            // Data buffer for incoming data.
            byte[] bytes = new Byte[1024];

            // Establish the local endpoint for the socket.
            // The DNS name of the computer
            // running the listener is "host.contoso.com".
            //IPHostEntry ipHostInfo = new IPHostEntry();
            IPAddress ipAddress = IPAddress.Any;
            IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);

            // Create a TCP/IP socket.
            Socket listener = new Socket(AddressFamily.InterNetwork,
                SocketType.Stream, ProtocolType.Tcp);

            // Bind the socket to the local endpoint and listen for incoming connections.
            try
            {
                listener.Bind(localEndPoint);
                listener.Listen(100);

                while (true)
                {
                    // Set the event to nonsignaled state.
                    allDone.Reset();

                    // Start an asynchronous socket to listen for connections.
                    Console.WriteLine("Waiting for a connection...");
                    listener.BeginAccept(
                        new AsyncCallback(AcceptCallback),
                        listener);

                    // Wait until a connection is made before continuing.
                }

            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }



        }

        public static void AcceptCallback(IAsyncResult ar)
        {
            // Signal the main thread to continue.
            allDone.Set();

            // Get the socket that handles the client request.
            Socket listener = (Socket)ar.AsyncState;
            Socket handler = listener.EndAccept(ar);

            // Create the state object.
            StateObject state = new StateObject();
            state.workSocket = handler;
            handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                new AsyncCallback(ReadCallback), state);
        }

        public static void ReadCallback(IAsyncResult ar)
        {
            String content = String.Empty;

            // Retrieve the state object and the handler socket
            // from the asynchronous state object.
            StateObject state = (StateObject)ar.AsyncState;
            Socket handler = state.workSocket;

            // Read data from the client socket. 
            int bytesRead = handler.EndReceive(ar);

            if (bytesRead > 0)
            {
                // There  might be more data, so store the data received so far.
                state.sb.Append(Encoding.ASCII.GetString(
                    state.buffer, 0, bytesRead));

                // Check for end-of-file tag. If it is not there, read 
                // more data.
                content = state.sb.ToString();
                if (content.IndexOf("<EOF>") > -1)
                {
                    // All the data has been read from the 
                    // client. Display it on the console.
                    Console.WriteLine("Read {0} bytes from socket. \n Data : {1}",
                        content.Length, content);
                    // Echo the data back to the client.
                    Send(handler, content);
                }
                else
                {
                    // Not all data received. Get more.
                    handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                    new AsyncCallback(ReadCallback), state);
                }
            }
        }

        private static void Send(Socket handler, String data)
        {
            // Convert the string data to byte data using ASCII encoding.
            byte[] byteData = Encoding.ASCII.GetBytes(data);

            // Begin sending the data to the remote device.
            handler.BeginSend(byteData, 0, byteData.Length, 0,
                new AsyncCallback(SendCallback), handler);
        }

        private static void SendCallback(IAsyncResult ar)
        {
            try
            {
                // Retrieve the socket from the state object.
                Socket handler = (Socket)ar.AsyncState;

                // Complete sending the data to the remote device.
                int bytesSent = handler.EndSend(ar);
                Console.WriteLine("Sent {0} bytes to client.", bytesSent);

                handler.Shutdown(SocketShutdown.Both);
                handler.Close();

            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
        }
    }
}
        //public static Socket Listener;
        //public static List<SocketAsyncEventArgs> ListenerEventArgs = new List<SocketAsyncEventArgs>();
        //public static List<Socket> ConnectedSockets = new List<Socket>();
        //public static void Bind()
        //{
        //    Listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        //    Listener.ReceiveTimeout = Config.ReceiveTimeout;
        //    Listener.SendTimeout = Config.SendTimeout;
            
        //    //TODO: Read IP / PORT from config
        //    IPAddress oHostIP = IPAddress.Any;
        //    IPEndPoint oEndPoint = new IPEndPoint(oHostIP, 25);
        //    Binder.Listener.Bind(oEndPoint);
        //    //Listener.AcceptAsync(new AsyncCallback(acceptCallback));
        //    // start listening
        //    Binder.Listener.Listen(Config.ConnectionQueue);

        //    Listener.BeginAccept( new pEventArgs_Completed(
        //}

        //static void pEventArgs_Completed((SocketAsyncEventArgs e)
        //{
        //    switch (e.LastOperation)
        //    {
        //        case SocketAsyncOperation.Connect:
        //            {
        //                SocketAsyncEventArgs pEventArgs = new SocketAsyncEventArgs();
        //                pEventArgs.Completed += new EventHandler<SocketAsyncEventArgs>(pEventArgs_Completed);
        //                e.ConnectSocket.AcceptAsync(pEventArgs);
        //            }
        //            break;
        //        case SocketAsyncOperation.Accept:
        //            {
        //                SocketAsyncEventArgs pEventArgs = new SocketAsyncEventArgs();
        //                pEventArgs.Completed += new EventHandler<SocketAsyncEventArgs>(pEventArgs_Completed);
        //                e.AcceptSocket.EndAccept(new AsyncCallback(pEventArgs_Completed));
        //            }
        //            break;
        //       }
        //}

        //static void ProcessConnect(SocketAsyncEventArgs e)
        //{
        //    if (e.SocketError == SocketError.Success)
        //    {
        //        // Successfully connected to the server
        //        byte[] buffer = Encoding.UTF8.GetBytes(Config.WelcomeMessage);
        //        e.SetBuffer(buffer, 0, buffer.Length);
        //        Socket sock = e.UserToken as Socket;
        //        bool willRaiseEvent = sock.SendAsync(e);
        //        if (!willRaiseEvent)
        //        {
        //            ProcessSend(e);
        //        }
        //    }
        //    else
        //    {
        //        throw new SocketException((int)e.SocketError);
        //    }
        //}
        //// Called when a SendAsync operation completes
        //public static void ProcessSend(SocketAsyncEventArgs e)
        //{
        //    if (e.SocketError == SocketError.Success)
        //    {
        //        // Sent "Hello World" to the server successfully

        //        //Read data sent from the server
        //        Socket sock = e.UserToken as Socket;
        //        bool willRaiseEvent = sock.ReceiveAsync(e);
        //        if (!willRaiseEvent)
        //        {
        //            ProcessReceive(e);
        //        }
        //    }
        //    else
        //    {
        //        //throw new SocketException((int)e.SocketError);
        //    }
        //}

        //public static void ProcessReceive(SocketAsyncEventArgs e)
        //{
        //    if (e.SocketError == SocketError.Success)
        //    {
        //        // Received data from server

        //        // Data has now been sent and received from the server. 
        //        // Disconnect from the server
        //        Socket sock = e.UserToken as Socket;
        //        sock.Shutdown(SocketShutdown.Send);
        //        sock.Close();
        //        //clientDone.Set();
        //    }
        //    else
        //    {
        //        //throw new SocketException((int)e.SocketError);
        //    }
        //}
        //static void pSendCompleted_Completed(object sender, SocketAsyncEventArgs e)
        //{

        //}
        //static void UnBind()
        //{
            
        //}
    

